Methylphenidate HCl, CAS No. 298-59-9, is prescribed primarily to treat attention-deficit/hyperactivity disorder in children. Methylphenidate HCl is currently available as a solid based capsule or tablet, typically in 5 mg or higher dosages. Solid based formulations have inherent limitations, as capsules and tablets can be difficult to subdivide. It is therefore difficult to precisely administer any dosage other than multiples of the standard available dosages. Further, capsules and tablets present swallowing difficulties for some patients. A liquid formulation of methylphenidate HCl is therefore desirable.
Unfortunately, methylphenidate HCl has not been chemically stable in conventional liquid vehicles. The primary route of methylphenidate HCl degradation in solution is hydrolysis resulting in the formation of threo-α-phenyl-2-piperidineacetic acid (major) and 2-piperidineacetic acid, α-phenyl-methyl ester (minor) compounds. In addition to stability, the methylphenidate HCl solution must be pharmaceutically acceptable and have an acceptable taste.
It is therefore desirable to provide a methylphenidate HCl solution that is chemically stable, pharmaceutically acceptable and palatable.